Conventionally, for example, Patent Literature 1 discloses a power supply apparatus for vehicles. The power supply apparatus includes a battery block including a plurality of unit batteries that are provided with safety valves, an exhaust duct that is coupled with opening parts of the safety valves of the unit batteries constituting the battery block and that ejects ejection matter from the opened safety valves, and control devices that are connected with the battery block and that control the charge and discharge of the unit batteries. In the battery block, the unit batteries are arrayed such that the opening parts of the safety valves are positioned on an identical plane. Further, in the power supply apparatus, the control devices are provided so as to face the safety valve opening plane of the battery block on which the opening parts of the safety valves are positioned. Furthermore, in the power supply apparatus, the exhaust duct is arranged between the control devices and the safety valve opening plane, and the exhaust duct thermally insulates the control devices from the battery block. Patent Literature 1 describes that, according to such a power supply apparatus, it is possible to reduce the external shape and increase the output of the battery block, and thus arrange the control devices such that they are thermally insulated from the heat of the battery block.